Originally Posted by Ricky Bobby

1) Is adding a secondary filtration (with a drain back to sump, ProVent100 or similar) redundant in anyway to be used in conjunction with the stock setup?

Not redundant, additive. I.E. - I am using secondary filtration with an OEM cyclonic separator and oem (318ti) PCV.

Is it even worth it to be used in line with the OEM Cold Weather CCV on the I6/M54?

The root cause of excess consumption must be diagnosed. It could prove beneficial to use secondary filtration in line. I fight high crankcase pressure largely from the SC. Is there a root cause that can be fixed?

2) Would it be more prudent to add a PCV check valve on the inlet line to the ProVent, bypass the OEM CCV completely and utilize a ProVent in its place, with a drain back to the dipstick tube and a return line to the valve cover, similar to OEM plumbing but with a serviceable filtration system, etc?

PCV is always last before hitting the intake air.

A clean PCV is a long lasting PCV. Could a ProVent replace a cyclonic separator? Sure, and you'd have the available drain. BUT, you now have to design for a PCV at the ProVent outlet since the OEM 6 cyl separator/PCV is one piece.

Yes I am in agreement that catch cans are moisture collectors but at the same token would we not be benefitting from removing the excess moisture collected in the can, assuming that it is better to drain a catch can bi-weekly at most in colder months but not have condensation buildup in the crankcase?

Condensation will always be building in the case. It should heat and steam and go away on a drive cycle. That moisture shouldn't collect in a can. The system should be hot hot hot to keep any form of condensation at bay. Metal catch cans bolted to frame is a giant heat sink. Long lines allow for cooling. A non draining catch can (condensing machine) becomes less "effective" with every use until suction draws a lot of fluid into the intake all at once and failure occurs. In my mind there is a VAST difference between a draining separator and a catch can. I do not agree with the idea, engineering, or maintenance of a "can".

At the end of the day I am way overthinking this, my June 2014 replacement Cold weather CCV and updated dipstick guide tube on my M54 is causing me zero issues. However, if I can get a similar mpg and "peppiness" bump that you got from the ProVent100 I would look into "additions" on the system. I have somewhat reduced consumption since installing, but would like to reduce that further if possible.

Everything should be made as simple as possible, but not simpler.